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Catalytic domain of the Serine/Threonine protein kinase, Vaccinia Related Kinase 1 STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. VRKs were initially discovered due to its similarity to vaccinia virus B1R STK, which is important for viral replication. Vertebrates contain three VRK proteins. Human VRK1 is implicated in the regulation of many cellular processes including cell cycle progression and proliferation, stress responses, nuclear envelope assembly and chromatin condensation. It regulates cell cycle progression during the DNA replication period by inducing cyclin D1 expression. VRK1 also phosphorylates and regulates some transcription factors including p53, c-Jun, ATF2, and nuclear factor BAF. VRK1 stabilizes p53 by interfering with its mdm2-mediated degradation. Accumulation of p53, which blocks cell growth and division, is modulated by an autoregulatory loop between p53 and VRK1 (accumulated p53 downregulates VRK1). This autoregulatory loop has been found to be nonfunctional in some lung carcinomas. The VRK1 subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",